Development of Binderless Graphite Compact for Bipolar Plate Production

Abstract

Bipolar plates account for almost 29% of the fuel cell stack costs and hence cost-effective manufacturing methods for making the bipolar plates are of paramount importance. Current manufacturing technologies for graphite bipolar plates require consolidation of graphite precursor materials using compression or injection molding followed by high temperature treatment for baking and graphitization. In contrast, in this investigation, we demonstrate direct consolidation of graphite powders without the use of any coal, petroleum or polymer binders resulting in significant reduction of time during compression molding as well as elimination of the need for additional heat treatment. Graphite particles were electrolessly coated with copper particles and subject to uniaxial compression at 100°C to produce a highly dense compact with relative density of ~ 98%, The process resulted in improving the flexural strength of the compact by almost ~50%. TEM investigation of the graphite particle interfaces revealed that copper undergoes creep deformation that aids in strengthening the compacts. The paper will describe the underlying mechanisms for the binderless production of graphite compacts which could be potentially useful for energy and cost-effective production of bipolar plates for fuel cells and flow batteries.